Best Handgun Cartridges for Three Gun Competitions: 9mm, .40, .38 Super

Choosing the right handgun cartridge for three gun competitions doesn’t have to be complicated. While concealed carry debates rage on with hundreds of calibers and cartridges, three gun is much simpler—only a few cartridges dominate the sport. Whether you’re competing to win or just to enjoy the match, your handgun setup matters.

Before we break down the top three handgun cartridges for three gun, it’s important to understand power factor and how it affects your choice.

Understanding Power Factor in Three Gun

In most shooting competitions, you’ll chrono your ammo to determine velocity and calculate power factor (PF). The formula is:

(Bullet Weight × Velocity) ÷ 1000 = Power Factor

• Minor Power Factor: 125+

• Major Power Factor: 165+

In three gun, you only need to meet the minor threshold (125 PF). Unlike USPSA, there’s no scoring advantage for shooting a major power factor cartridge—only more recoil and slower follow-up shots. That’s why most shooters stick to minor PF cartridges, especially 9mm, but there are reasons you might choose alternatives like .40 S&W or .38 Super.

1. 9mm Luger (The Standard Choice)

The 9mm Luger is the most common handgun cartridge in three gun competitions, and for good reason. Factory loads easily clear the minor power factor, while offering soft recoil, excellent reliability, and high magazine capacity.

Why 9mm Works Best:

• Factory loads = low recoil, reliable cycling

• Widely available and affordable

• Large capacity within the 170mm magazine limit

• Excellent for reloading if you want custom match ammo

Best Handguns for 9mm in Three Gun:

• Sig P320 XFive

• Glock 34 or Glock 17

Since divisions like Tactical Optics, Limited, Open, and 2-Gun all allow 9mm, it’s no surprise that most shooters stick with this cartridge.

2. .40 Smith & Wesson (The Versatile Option)

The .40 S&W may not be as popular as 9mm in three gun today, but it’s still a solid choice—especially if you compete across multiple shooting disciplines. Factory loads often sit right on the edge of major power factor, which is useful in USPSA and other competitions, even if it doesn’t matter in three gun.

Why Choose .40 S&W:

• Passes minor PF easily, capable of major PF in other sports

• Good magazine capacity (though less than 9mm)

• Ideal for shooters who already carry a .40-caliber duty pistol

Recommended .40 S&W Pistols:

• CZ Tactical Sport 2

• Glock 22 or Glock 35

• Smith & Wesson M&P40

If you want a handgun that can pull double-duty between three gun and USPSA, .40 S&W is a smart investment.

3. .38 Super (The Competition Cartridge)

The .38 Super is a high-pressure cartridge that delivers speed, flat trajectory, and excellent compensator performance. It uses the same bullet diameter as 9mm but with a longer case, allowing for higher velocity and more energy.

Why .38 Super Stands Out:

• Can hit major power factor with +P loads or handloads

• Excellent for compensated pistols (reduced recoil and faster cycling)

• Similar magazine capacity to 9mm in 170mm mags (around 28 rounds)

• Flexible: load down to minor PF or push to major PF

Best .38 Super Pistols for Competition:

• STI 2011

• Custom 1911 platforms

• 38 Super Comp variants for more reliable feeding

If you compete in divisions that allow compensators, .38 Super can give you a significant edge in recoil control and cycling speed.

Final Thoughts: Picking the Right Handgun Cartridge

For most new shooters, 9mm is the best choice for three gun—it’s affordable, soft-shooting, and supported across every division. But if you compete in multiple disciplines, .40 S&W offers flexibility, while .38 Super gives you competition-level performance with the ability to meet major power factor.

At the end of the day, the best cartridge is the one that matches your goals, budget, and competition rules. Start with 9mm if you’re new, but don’t be afraid to explore other calibers once you’re ready to expand your horizons.